Artificial turf

ABSTRACT

An artificial turf for a synthetic field system includes a flexible, water-permeable backing, a pile fabric woven into the backing, and a limited layer of water-absorbent, eco-friendly and light reflective infill deposited within voids formed in the pile fabric. The pile fabric is constructed with a plurality of separate, upwardly standing, reduced height tufts, each tuft including a plurality of synthetic filaments that resemble individual blades of natural grass. The tufts are arranged into parallel rows, with the spacing between rows being fixed and equal to the spacing between successive tufts in each row so as to yield an artificial field surface with an increased density of filaments. The dimensional aspects and high filament density of the artificial turf introduces a number of notable advantages over conventional artificial turfs including better performance, less surface heat retention, improved aesthetics, reduced infill maintenance requirements, and greater compliance with environmental standards.

FIELD OF THE INVENTION

The present invention relates generally to sports field playing surfaces and, more particularly, to artificial turf systems designed to replicate natural grass playing surfaces.

BACKGROUND OF THE INVENTION

Artificial, or synthetic, turf systems are well-known in the art and are commonly utilized as a low maintenance alternative to traditional grass field playing surfaces. Artificial turf systems typically comprise a firm, stable and impervious subsurface, or aggregate base, on which a water-permeable artificial turf is mounted. Preferably, a drainage blanket with a water impermeable barrier on its bottom surface is disposed between the stable subsurface and the artificial turf to promote lateral, or horizontal, drainage of water. Accordingly, rain is designed to readily penetrate through the artificial turf and into lateral channels formed in the drainage blanket which are then diverted horizontally to a drainage system in order to prevent saturation on the field surface.

In U.S. Pat. No. 7,128,497 to D. Daluise, the disclosure of which is incorporated herein by reference, there is shown an example of an artificial turf system of the type as described above. Specifically, a horizontally draining artificial turf system is provided which includes an impervious base at proper slope, an impermeable layer or drainage blanket over the base at a corresponding slope for guiding water horizontally, an artificial turf on top of the impermeable layer, and a perforated pipe near the lower edge of the base for receiving water for evacuation. Rainwater over the artificial turf first drains vertically onto the impermeable layer and then flows along the impermeable layer to reach the perforated pipe, without infiltrating into the base. Alternatively, a partially pervious drainage blanket is provided in lieu of the impermeable layer where the base is partially pervious. Backup rainwater runs off the drainage blanket horizontally after it saturates the soils of the base.

Referring now to FIGS. 1 and 2, there are shown cross-sectional and bottom perspective views, respectively, of one type of prior art artificial turf 11 that is commonly utilized in synthetic turf systems. For instance, artificial turf 11 may be of the type shown in U.S. Pat. No. 4,337,283 to F. Haas, Jr., the disclosure of which is incorporated herein by reference. As seen most clearly in FIG. 1, artificial turf 11 includes a water-permeable backing 13 to which a plurality of elongated, continuous yarns 15 are woven, or stitched, along corresponding linear paths, each yarn 15 commonly including a plurality of individual synthetic filaments 17 that are braided, twisted, or otherwise joined together.

As part of the stitching process, each yarn 15 is downwardly needled through backing 13. Disposed beneath the underside of backing 13, the needle is then spaced a fixed stitch distance along the linear path (this metric being commonly referred to in the art as the “back stitch length”) and then inserted upward through backing 13 to a predetermined height above the top surface of backing 13. Thereafter, yarn 15 is looped and downwardly needled through backing 13 once again, with the process repeating along the linear path. To help permanently secure each yarn 15 to backing 13, the underside of backing 13 is subsequently applied with a resinous coating.

The exposed upstanding piles formed in yarn 15 are then subsequently cut along a common plane to form a plurality of tufts, or clusters, 19 of individual filaments 17, each tuft 19 partially unravelling or otherwise separating at its distal end. In this capacity, the distal ends of synthetic filaments 17 form generally vertical strands that are preferably dimensioned, shaped and colored to resemble blades of natural grass.

A relatively substantial layer of infill, or top-dressing, 21 is then evenly deposited onto backing 13 within the voids formed between tufts 19 to provide the principal support surface for artificial turf 11. Traditionally, infill 21 is formed as a mixture consisting of resilient particles and fine sand.

The design specifications associated with artificial turf 11 typically fall within a standardized range. For instance, the overall height H of each tuft 19 is traditionally relatively long, often in the order of 2.25 inches or greater. Additionally, the depth D of infill 21 is traditionally relatively substantial, often in the order of 1.75 inches or greater, so as to achieve a filament relief value R (i.e., the length of each tuft 19 above infill) of approximately 0.50 inches. Furthermore, the face-weight of the plurality of filaments 17 (i.e., the weight of filaments 17 per square yard) is traditionally relatively light, often in the range between 30 and 48 ounces, in order to compensate for the considerable weight associated with the substantial amount of infill 21.

Artificial turf 11 is typically constructed with tufts 19 arranged in a grid-like configuration. Specifically, as seen most clearly in FIG. 2, the plurality of yarns 15 are woven into backing 13 along parallel rows 22 that are equidistantly spaced apart.

However, it should be noted that artificial turf 11 is typically manufactured with tufts 19 arranged in a grid with adjacent tufts 19 disposed in a rectangular configuration, or pattern. As can be seen, the fixed spacing between adjacent tufts 19 in the X direction is greater than the fixed spacing between adjacent tufts 19 in the Y direction (this construction being referred to herein simply as a rectangular stitch construction). In other words, the stitch gauge G (i.e., the spacing, or gap, between adjacent stitch rows, or lines, 22 in the X direction in FIG. 2) is considerably greater than the back stitch length, or stitch width, W (i.e., the spacing between midpoints of successive stitches in the Y direction in FIG. 2). Specifically, the stitch gauge G of traditional turf 11 is relatively substantial, often in the order of 0.75 inches, whereas the stitch width W is typically a fraction thereof, often in the order of 0.25 inches. Commonly, stitch count (i.e., the number of stitches for each yarn 15 per 3 inches) is utilized as the industry metric associated with the width of each stitch, with the stitch count for traditional turfs being typically in the order of 12.

A rectangular stitch construction and, in particular, a widened stitch gauge is commonly utilized in traditional artificial turfs for a couple of reasons. Primarily, when a non-permeable backing is utilized, a widened stitch gauge is required in order to facilitate the cutting of openings between stitch rows and thereby allow for water penetration into the drainage blanket. For example, in U.S. Pat. No. 5,976,645 to D. Daluise et al., the disclosure of which is incorporated herein by reference, there is disclosed a process of perforating a non-permeable backing with holes spaced approximately 2.0-8.0 inches apart, with each hole having a preferred diameter in the range of approximately 0.1-0.75 inches. Additionally, a widened stitch gauge is often required to minimize the overall filament face-weight.

As can be appreciated, it has been found that the rectangular stitch construction of traditional artificial turfs significantly limits the density of tufted filaments and, as a consequence, introduces a number of notable shortcomings.

As a first shortcoming, the limited filament density places a greater reliance on the turf infill as the primary support surface, with the filaments functioning primarily to retain the infill in place. The use of the infill as the principal support surface is undesirable for a multitude of reasons including, but not limited to, (i) inadequate performance due to inconsistency, instability as well as uneven force response and shock attenuation associated with the infill, (ii) the requirement of a greater infill depth, thereby increasing costs as well as surface heat, and (iii) the reliance upon routine field maintenance in order to periodically replace and/or redistribute the infill.

As a second shortcoming, the rectangular stitch construction of traditional artificial turfs creates an unpleasant appearance, which is often perceivable when viewed on high definition television. Poor aesthetics result from, inter alia, perceivable stitch lines (often referred to in the art as “corn-rowing”) that result from using too wide a stitch gauge, visible displacement or “fly-out” of the poorly retained infill, and lay-over, or pile-crush, of the longer length and sparse arrangement of filaments (i.e., rather than extend in a near vertical orientation, the filaments tend to fold over, or flatten, into a near horizontal orientation, this condition often compromising performance as well as resulting in the unwanted retention of heat in the field surface).

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to provide a new and improved artificial turf for a synthetic turf system.

It is another object of the present invention to provide an artificial turf as described above that exhibits optimal performance characteristics.

It is yet another object of the present invention to provide an artificial turf as described above that aesthetically pleasing.

It is still another object of the present invention to provide an artificial turf as described above that minimizes the retention of heat on the playing surface.

It is yet still another object of the present invention to provide an artificial turf as described above that is environmentally-friendly.

It is another object of the present invention to provide an artificial turf as described above that has a limited number of components, is inexpensive to manufacture and easy to install.

Accordingly, as a principal feature of the present invention, there is provided an artificial turf comprising (a) a flexible backing, (b) a pile fabric woven in the flexible backing, the pile fabric including a plurality of separate, upwardly standing tufts that are arranged in a series of parallel rows, wherein adjacent tufts within each of the series of rows are spaced apart a fixed width, wherein adjacent rows in the series of parallel rows are spaced apart a fixed spacing, and (c) an infill deposited on the flexible backing between the plurality of tufts, (d) wherein the width between adjacent tufts within each of the series of rows is equal to the spacing between adjacent rows in the series of parallel rows.

Various other features and advantages will appear from the description to follow. In the description, reference is made to the accompanying drawings which form a part thereof, and in which is shown by way of illustration, various embodiments for practicing the invention. The embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. The following detailed description is therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings wherein like reference numerals represent like parts:

FIG. 1 is a longitudinal cross-sectional view of an artificial turf which is well-known in the art;

FIG. 2 is a bottom perspective view of the prior art turf shown in FIG. 1;

FIG. 3 is a longitudinal cross-sectional view of an artificial turf constructed according to the teachings of the present invention; and

FIG. 4 is a bottom perspective view of the artificial turf shown in FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION Construction of Artificial Turf 111

Referring now to FIGS. 3 and 4, there is shown an artificial turf constructed according to the teachings of the present invention, the artificial turf being identified generally by reference numeral 111. As will be described in detail below, artificial turf 111 relies upon a square stitch construction which, in turn, provides a number of notable advantages.

As seen most clearly in FIG. 3, artificial turf 111 is similar to prior art turf 11 in that artificial turf 111 comprises a flexible backing 113, a pile fabric 115 woven into backing 113, and a granular infill 117 deposited within voids formed in pile fabric 115.

Backing 113 is preferably constructed as a unitary, water-permeable member that supports pile fabric 115 and infill 117, backing 113 including a top surface 119 and a bottom surface 121 which is preferably disposed in direct contact against a horizontal drainage blanket (not shown). It is to be understood that backing 113 may rely upon a multilayer construction. In particular, backing 113 preferably includes a primary, or upper, layer 113-1 constructed using one or more sheets of woven fabrics, such as polypropylene, polyester or other synthetic materials, and a secondary, or lower, layer 113-2 in the form of a polymeric coating which is applied to the underside of upper layer 113-1 and subsequently heat-cured, as will be described further below.

Pile fabric 115 is constructed as a sheet of material with a plurality of normally upstanding loops or strands, the distal ends of which together define a raised and generally planar top surface. In the present embodiment, pile fabric 115 is formed by stitching (i.e., weaving in-and-out) a plurality of elongated, continuous yarns 123 through backing 113 along corresponding stitch lines, or rows, 124 each yarn 123 comprising a plurality of individual synthetic filaments 125 that are braided, twisted or otherwise joined together.

In a manner similar to the construction of artificial turf 11, each yarn 123 is downwardly needled through backing 113 (i.e., in the direction from top surface 119 to bottom surface 121). Disposed beneath bottom surface 121, the needle is spaced a fixed stitch distance, or back stitch length, along the linear path and then inserted back upward through backing 113 (i.e., the direction from bottom surface 121 to top surface 119) to a predetermined height above top surface 121. Thereafter, each yarn 123 is looped and downwardly needled through backing 113 once again, with the process repeating along the linear path. To facilitate securement of pile fabric 115 to backing 113, secondary layer 113-2 is preferably applied to the underside of upper layer 113-1 and subsequently heat-cured upon completion of the aforementioned yarn weaving process.

As part of a subsequent manufacturing step, the exposed looped portions of the plurality of yarns 123 are cut along a common plane to form a plurality of separate filament tufts 127, each tuft 127 partially unravelling or separating at its distal end. As such, the plurality of individual filaments 125 in each tuft 127 separate into generally vertical strands which are preferably dimensioned, shaped and colored to resemble individual blades of natural grass.

As referenced briefly above, infill 117 is deposited within voids formed in pile fabric 115 and serves, inter alia, to provide enhanced structural support for pile fabric 115. Infill 117 is preferably constructed as a mixture which includes a plurality of resilient granular particles that are preferably light reflective, free of synthetic materials, free of silica sand, environmentally-friendly, ecologically-safe, and non-supportive of microbial growth. For instance, infill 117 may be of the type disclosed in U.S. Patent Application Publication No. 2010/0055461 to D. Daluise et al., the disclosure of which is incorporated herein by reference.

As another example, infill 117 may consist of a relatively expensive mixture of microporous, aluminosilicate minerals, such as Zeolite, a synthetic rubber, such as ethylene propylene diene monomer (EPDM) rubber, and ground walnut shell. In this capacity, the Zeolite provides water absorption capabilities to aid in evaporative cooling and thereby reduce surface heat on the playing field. Additionally, the EPDM rubber provides the resiliency necessary to maintain performance standards with respect to force reduction, energy restitution and vertical deformation. For reasons to become apparent below, a relatively expensive infill mixture can be utilized without increasing overall manufacturing costs.

Artificial turf 111 is similar to artificial turf 11 in that artificial turf 111 is constructed with its tufts 127 arranged in a grid-like configuration. Specifically, yarns 123 are woven into backing 113 along equidistantly spaced, parallel rows 124 (i.e., the spacing between adjacent stitch lines in the X direction in FIG. 4 is fixed). Furthermore, each yarn 123 is woven into backing 113 using a common stitch size, or count (i.e., the spacing between adjacent tufts 127 within each row 124, which is measured as the distance between midpoints of successive stitches in the Y direction in FIG. 4, is fixed).

Artificial turf 111 primarily differs from artificial turf 11 in that artificial turf 111 is constructed with tufts 127 arranged in a grid with adjacent tufts 19 disposed in a square configuration, or pattern (this construction being referred to herein simply as a square stitch construction). As can be appreciated, the use of a square stitch construction substantially increases the density of filaments 125 (e.g., by a factor of three or more in relation to artificial turf 11). As will be described further below, the substantial increase in filament, or blade, density allows for significant modification to certain design specifications.

Referring now to FIG. 4, the square stitch construction utilized for artificial turf 111 is readily apparent. Specifically, as can be seen, the stitch gauge G′ (i.e., the spacing between adjacent stitch lines, or rows, in the X direction) is generally equal to the stitch width W′ (i.e., the spacing between midpoints of successive filament stitches in the Y direction). In the present embodiment, the stitch gauge G′ of turf 111 is preferably 0.25 inches or less, whereas the stitch width W′ is selected in accordance therewith (e.g., 0.25 inches or less). Because stitch count (i.e., the number of stitches per 3 inches) is utilized as the industry metric associated with the width of each stitch, it should be noted that the stitch count value for turf 111 would be approximately 12 for a stitch gauge G′ of 0.25 inches.

It should be noted artificial turf 111 is not limited to the corresponding stitch gauge and stitch width values provided above. Rather, it is to be understood that the stitch gauge and stitch width values for artificial turf 111 could be modified without departing from the spirit of the present invention as long as the modified stitch gauge and stitch width values yields a turf construction with adjacent tufts 127 arranged in a fixed square pattern.

It should also be noted that the considerable narrowing of stitch gauge G′ in artificial turf 111 enables a corresponding decrease in stitch rate to be utilized. This reduction in the number of tufts 127 along each stitch line results in a longer back stitch which, in turn, yields more surface area contact with polymeric coating 113-2 applied to the underside of backing 113 and, therefore, a better tuft bind. Additionally, a decreased stitch rate increases the spacing between adjacent tufts 127 along the stitch line, which allows for greater deposition of infill 117 between adjacent tufts 127, thereby providing greater resistance to lay-over of filaments 125. Creating a greater resistance to filament lay-over not only improves performance (by minimizing directional force response) but also limits the retention of heat on the playing surface.

As referenced briefly above, the square stitch construction of turf 111 increases tuft and filament density which, in turn, allows for significant modification to certain design specifications. For instance, in the present embodiment, the overall height H′ of each tuft 127 is considerably shortened, with a preferred value of 1.75 inches or less. Additionally, the depth D′ of infill 117 is substantially reduced, with a preferred value of 1.0 inches or less, in order to achieve a significant filament relief value R′ (i.e., the length of each tuft above infill) of at least 0.75 inches. Furthermore, the face-weight of pile fabric 115 (i.e., the weight of high density filaments 127 per square yard) can be raised to 60 ounces or greater (and preferably in the range of 60-64 ounces) because of the reduction in weight associated with limited supply of infill 117.

Features and Benefits of Design of Artificial Turf 111

As referenced above, artificial turf 111 utilizes a square stitch construction (i.e., a square-based arrangement of adjacent tufts 129) which, in turn, increases the overall density of filaments 127. This increase in filament, or blade, density, enables a number of notable advantages to be realized as compared to traditional artificial turfs (e.g., prior art turf 11) which rely upon a rectangular stitch construction.

As a first feature, the increased blade density of artificial turf 111 places a greater reliance upon individual filaments 127 as the primary support surface, with infill 117 as well as the synthetic aggregate base on which turf 11 is ultimately mounted providing supplemental support to filaments 127. As a result, the resultant synthetic field system is better designed to absorb forces and attenuate shock (i.e., allow for accelerated impact force response rates). By contrast, traditional turfs that rely predominantly on the infill as the support surface experience inconsistent directional performance as a result of the inherent, and often counterproductive, softness of a rubber-based infill.

As a second feature, the increased blade density of artificial turf 111 enables less infill to be used, which, in turn, creates less heat on the field surface, lowers overall costs, minimizes field maintenance requirements, and improves reliability of performance since largely infill-based surfaces have been found to experience considerable changes in moisture content, stratification and compaction over time. Furthermore, because substantially less infill is required, a slightly more expensive infill mixture can be utilized that is (i) ecologically safe, (ii) light reflective and/or (iii) water-absorbent (i.e., to reduce heat retention on the field surface).

As a third feature, the increased blade density of artificial turf 111 improves the overall aesthetics of the field because the reduction in stitch gauge renders the stitch lines unperceivable even when viewed under high definition television. Furthermore, the increased blade density serves to more adequately restrict movement of the infill which, as a result, (i) significantly limits the occurrence of visibly perceivable infill fly-out and (ii) minimizes the frequency of maintenance required in order to redistribute and/or replenish the infill.

As a fourth feature, the increased blade density of artificial turf 111 enables shorter length filaments to be used. As a result, filament lay-over, or matting, is largely eliminated as the individual blades have been found to maintain a near vertical orientation, even after considerable use. The elimination of filament lay-over serves, inter alia, to improve performance (e.g., with respect to traction, wear, ball-speed, shock absorption and rotational resistance), create a more aesthetically pleasing appearance, and minimize surface heat (since blade lay-over has been found to trap heat within the active field surface).

It is to be understood that the particular construction of artificial turf 111 is intended to be merely exemplary and those skilled in the art shall be able to make numerous variations and modifications to it without departing from the spirit of the present invention. All such variations and modifications are intended to be within the scope of the present invention as defined in the appended claims. 

What is claimed is:
 1. An artificial turf comprising: (a) a flexible backing; (b) a pile fabric woven into the flexible backing, the pile fabric including a plurality of separate, upwardly standing tufts that are arranged in a series of parallel rows, wherein adjacent tufts within each of the series of rows are spaced apart a fixed width, wherein adjacent rows in the series of parallel rows are spaced apart a fixed spacing; and (c) an infill deposited on the flexible backing between the plurality of tufts; (d) wherein the width between adjacent tufts within each of the series of rows is equal to the spacing between adjacent rows in the series of parallel rows.
 2. The artificial turf as claimed in claim 1 wherein the pile fabric comprises a plurality of individual yarns that is woven through the backing to form the plurality of tufts, each of the plurality of yarns forming a corresponding row in the series of parallel rows.
 3. The artificial turf as claimed in claim 2 wherein each of the plurality of individual yarns includes a plurality of synthetic filaments.
 4. The artificial turf as claimed in claim 3 wherein the spacing between adjacent rows is at most 0.25 inches.
 5. The artificial turf as claimed in claim 4 wherein the width between adjacent tufts within each of the series of rows is at most 0.25 inches.
 6. The artificial turf as claimed in claim 5 wherein each of the plurality of tufts has an overall height that is not to exceed 1.75 inches.
 7. The artificial turf as claimed in claim 6 wherein the infill has a depth that is not to exceed 1.0 inches.
 8. The artificial turf as claimed in claim 7 wherein each of the plurality of tufts has a relief value of 0.75 inches.
 9. The artificial turf as claimed in claim 8 wherein the pile fabric has a face-weight of at least 60 ounces.
 10. The artificial turf as claimed in claim 9 wherein the infill is a mixture consisting of: (a) microporous, aluminosilicate minerals; (b) rubber particles; and (c) ground walnut shell.
 11. The artificial turf as claimed in claim 10 wherein the flexible backing is constructed as a unitary, water-permeable member.
 12. The artificial turf as claimed in claim x wherein the backing comprises: (a) an upper layer in the form of a woven fabric; and (b) a lower layer in the form of a polymeric coating. 